An attachment system for attaching an accessory to the muzzle end of a firearm includes an accessory such as a silencer or sound suppressor, a muzzle adapter, and a multi-functional assembly, disassembly and locking device that locks the muzzle adapter onto the body of the suppressor. An end of the device is also configured to mate with the muzzle adapter to provide torque to selectively assemble or disassemble the muzzle adapter to the suppressor.